Mud building/ cob houses

[Erika]

Hi,

I've just watched "first earth" which I found at PRi's homepage. I'm now looking for people who could help me with some advice on mud building.

I intended to build a wooden play house for my children this summer, but I've considered building with ferro cement (which i don't like because of the energy). I had put the mud building aside, because I haven't found any good information. But now I'm lost, I have to build a mud play house! I want to start now! But the snow is not yet gone! So I have time to plan.

I would need information on:

1. The ground moves a little during winter when it freezes, about 5 cms perhaps. What do I need to do to prevent the cottage from being damaged because of that?

2. The words mud, soil and earth are used in videos I've seen. On my ground I've sandy soil with gravel. I plan to dig out a damm in the future. Can I use sandy soil? What do I need to complement it with?

3. What can I mix in? Any kind of staw? Bark? Little twigs? It has to be dried, right?

4. Do I need to keep the walls wet while building? I will not finish it in one day!

5. I thought to do the roof in the same material. Could I use "chicken-net" to form it as i please and then cover it in mud? Or does it have to be covered with another roof material (straw?).


I'm so much looking forward to this!!!
I'll try to learn how to post photos here, so I can show the progress.

Best regards
Erika

[Mudman]

Erika,
All the best with your project, sounds like you are building with cob
Do a search for cob houses and you might find some more information.
I would recomend putting on a solid roof or maybe an earth roof.
I just did a google image search and came up with this place http://small-scale.net/yearofmud/
Cheers
Kurt

[Erika]

Thanks Kurt,
I'll check your link out.
I've watched videos, but they tend to be about the cheerful process of building, and don't give step by step instructions. But it's still very inspiering to see what's possible to create.

If anyone else need info like this or if you have good info or links, please post
It's rather timeconsuming sometimes to find good pages.

Regards from Erika

[sweetpea]

Aren't those cob houses the cutest things? They are very tempting to try. There's a lot of rammed earth housing happening in California. It makes very beautiful walls. You might want to look into it. Here's a site that has links and info:

http://www.diyrammedearth.com/

It's all done with clay soil, there's no getting around it, unless you want to add cement or concrete (not the posthole stuff) to your sand. there are lots of fascinating cement buildings, too. Great for insulation, fire protection.

And as you say, the heaving of soil is very serious, and the same engineering requirements are necessary for any type of housing. Foundations need to be below the frost line. So getting the engineering right is probably the most important thing. The village of cob houses are in Northern California where the soil doesn't freeze, and summers are dry, so it's probably an easier environment. The Spanish missionaries 200 years ago made missions from the clay in California. Some are still standing, but take a lot of maintenance. Again, no summer rain, so the bricks dry out in the summer. Let us know what you try

[Pakanohida]

http://www.cobcottage.com/

The above link is the working place for Ianto Evans, the man knows Cob and travels world wide teaching and learning about it. NZ Parliament building is made of cob! My (work in progress) outdoor kitchen is made of cob!

1. The ground moves a little during winter when it freezes, about 5 cms perhaps. What do I need to do to prevent the cottage from being damaged because of that?

A good foundation is what you will cheerfully need!

2. The words mud, soil and earth are used in videos I've seen. On my ground I've sandy soil with gravel. I plan to dig out a damm in the future. Can I use sandy soil? What do I need to complement it with?

You will need to test your soil, make test bricks, and you will most likely need to add clay and straw.

3. What can I mix in? Any kind of staw? Bark? Little twigs? It has to be dried, right?

Weed free straw. Bottles, cans, Time capsules of hemp seeds for the future.

4. Do I need to keep the walls wet while building? I will not finish it in one day!

Yes, it needs to dry slowly, I suggest reading Ianto's book.

5. I thought to do the roof in the same material. Could I use "chicken-net" to form it as i please and then cover it in mud? Or does it have to be covered with another roof material (straw?).

I know you can with hemp cloth and straw.. not sure about the lightweight cement approach, I would suggest emailing Cob Cottage direct.

[Pakanohida]

@Sweetpea

Up I-5, go onto 42S towards the town of Coos Bay and stop in "Coquille" after getting permission to visit Cob Cottage...

They are in temperate rainforest building a new Cob village. The place, for lack of better words is breath taking and inspiring.

[sweetpea]

Erika, while a mud roof might look cute, it's got to be engineered right. We just had a horrifying downpour for 3 days, and I've got conventional buildings, and things were leaking where they've never leaked before. You can't do anything at that point to try to save things if they aren't put together right. Or if there is a snow load, it's way better to make a rustic wooden roof with eaves that protect those walls. It's very, very dangerous to have such a structure just made out of chicken wire and mud, because there's very little structural integrity there. You might also look at how they made the California Missions, they all have wooden roofs. The standard homemade clay/straw bricks must be in the sun, no rain or dew on them, turned regularly for 30 days before using.

Pakanohida, yes, I saw all the You Tube pieces on those cob houses, and it's inspiring, although I am trying to have less and less maintenance, and I'm afraid those darling little things need maintenance more than one might realize.

[Mudman]

Erika,
Another option you could pursue is to build it out of strawbales.
You could get the walls up in a day and then have fun putting a clay render on with your kids.
Do a google search for strawbale in Sweden and there are a fair few over there.
Looks the same as cob but alot quicker to construct. Would give you very good insulation as well.
But definately put a proper roof on with wide overhangs.

Cheers
Kurt

[Erika]

Dear friends, thank you for all your replies! I've known of permaculture for a little more than two years and have don a PDC but it wasn't until recently I discovered this page. It's so good to have an ocean of people willing to share and support. Permaculture in Sweden is still small (as is Sweden!). Anyway...

Hm, I thought of straw-bale technique as more timeconsuming than cob, but I may well be wrong. And I got really eager to shape this little playhouse just as I wanted, and cob is so good for that. Possible with strawbale too, but not as easy...
Thanks for all roof-safety-warnings! I saw this fero-cement technique, and it's supposed to be very strong. So my reflection was that perhaps it was possible to replace the cement with cob. I've taken your warnings and will make a proper wooden one.
And a proper foundation. Since I was just planning a little playhouse I thought I might not have needed this. I want to build it just under a big birch, and there's a loot of roots in the ground. But, ok, I'll stick to the rules and figure something out!

So, for the time being, with this project being larger than I first thought, I guess I ought tobe greatful that I was just given a big pile og salix from a garden nearby. It's way much easier to build a "hut" from that. Only a few hours. It'll do, until I have more time.
http://www.google.se/images?hl=sv&rl...w=1899&bih=841

Please take care, and thank you again.
Erika

[pebble]

" NZ Parliament building is made of cob! "

Which building are you talking about? AFAIK none of the current parliament buildings are cob/earth buildings.